feat(require-ion-error-text): lint Ionic validation messages

[rdlabo]

Overview

Adds an Angular template lint rule that requires a valid Ionic error-text source for controls participating in Signal Forms validation.

The default scope is intentionally limited to supported Ionic controls with [formField], avoiding false positives for filters and settings controls that do not represent validation fields.

Changes

• Add require-ion-error-text
• Support ion-input, ion-textarea, ion-select, ion-checkbox, ion-radio-group, and ion-toggle
• Accept non-empty static errorText and property-bound [errorText]
• Reject empty text and [attr.errorText]
• Add adapter-aware, check-all, and readonly options
• Enable the rule in the recommended preset
• Document the 22.1 migration and configuration

Compatibility

The recommended preset gains a new error-level rule. The default only checks controls with [formField]; applications using KitIonicFormField can explicitly enable adapter-aware mode.

Validation

• npm run lint
• npm test -- --runInBand — 594 tests passed